On-line Measurement of the Surface Area Concentration of PM2.5 in Yokohama using Diffusion Charging Method

摘要

In the field of evaluating adverse health effects at exposures to nanomaterials, scientific interest has shifted from mass to surface area (SA) recently. In one of those studies, Oberdorster et al. (2005) proposed that SA is a more appropriate indicator than mass on an evaluation of pulmonary inflammatory response caused by dose of TiO2 particles to rats and mice. However, mass concentration is used currently as an index of toxicity when discussing adverse health effects caused by exposures to PM2.5. For instance, the guideline values for PM2.5 prescribed by WHO (2005) are 10 μg/m~3 (annual mean) and 25 μg/m~3 (24-hour mean). By now, there are some studies of measuring the SA of ambient aerosols with diffusion charging (DC) method (Albuquerque et al., 2012). However, long-term measurement of the SA of ambient aerosols in the same site has seldom been carried out. Therefore, measurement of the SA concentration of PM2.5 in Yokohama was conducted for 9 months in this study.